10) Mats Hummels (Borussia Dortmund)
Interested clubs: Arsenal, Manchester United, Barcelona, Real Madrid
One of the best defenders in the world, Borussia Dortmund centre-back Mats Hummels could be on the move this January, and recent reports suggest that Arsenal are in pole position to sign the German, with the Gunners undoubtedly in need of improvements to their back four.
Prediction: Arsenal